In contrast with the vibration isolation regime, which requires active elements, the gravity compensation can be provided in a passive manner, i.e., without the need for power consumption. This paper presents two types of electromagnetic actuators whose design focuses on the passive gravity compensation and, furthermore, incorporate active elements which provide adjustability of their force response characteristics. The first actuator type mimics the behavior of a mechanical spring, i.e., positive and constant force stiffness, while the second type is characterized by a constant-force response, i.e., zero force stiffness. Two design solutions are obtained by means of aggressive output space-mapping optimization, and their respective characteristics are discussed.

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